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What is the syntax for creating a trigger?
Syntax for creating trigger: CREATE [OR REPLACE ] TRIGGER trigger_name. {BEFORE | AFTER | INSTEAD OF } {INSERT [OR] | UPDATE [OR] | DELETE} [OF col_name]
What is trigger in Oracle with example?
A trigger is a named PL/SQL block stored in the Oracle Database and executed automatically when a triggering event takes place. For example, if you define a trigger that fires before an INSERT statement on the customers table, the trigger will fire once before a new row is inserted into the customers table.
What is the use of trigger in Oracle?
Traditionally, triggers supported the execution of a PL/SQL block when an INSERT , UPDATE , or DELETE occurred on a table or view. Starting with Oracle8i, triggers support system and other data events on DATABASE and SCHEMA . Oracle also supports the execution of a PL/SQL or Java procedure.
How does the create trigger statement in Oracle work?
CREATE TRIGGER Statement. The CREATE TRIGGER statement creates or replaces a database trigger, which is either of these: The database automatically runs a trigger when specified conditions occur. To create a trigger in your schema on a table in your schema or on your schema (SCHEMA), you must have the CREATE TRIGGER system privilege.
What causes trigger to fire in Oracle Database?
Performing DML operations directly on nested table columns does not cause Oracle Database to fire triggers defined on the table containing the nested table column. Specify one or more types of DDL statements that can cause the trigger to fire. You can create triggers for these events on DATABASE or SCHEMA unless otherwise noted.
What happens when the create trigger statement fails?
The PL/SQL block or CALL subprogram that the database runs to fire the trigger. A CALL subprogram is either a PL/SQL subprogram or a Java subprogram in a PL/SQL wrapper. If trigger_body is a PL/SQL block and it contains errors, then the CREATE [ OR REPLACE] statement fails.
What happens when a trigger is disabled in Oracle?
Note that if a trigger is disabled, it is not fired when the triggering event occurs. By default, if you don’t specify the clause ENABLE / DISABLE , the trigger is created with the enabled state. For each triggering event e.g., INSERT, UPDATE, or DELETE, you can define multiple triggers to fire.